1. Field of the Invention
The present invention relates to the detection of tampering or sabotage to a surveillance system such as an intrusion detection system or other system for which the detection of tampering or sabotage is desired.
2. Description of the Related Art
Surveillance systems such as intrusion detection systems may employ microwave radar systems and/or infrared sensors to detect the presence of an intruder in a protected space and typically generate an alarm signal, such as an electrical signal communicated to a central monitoring station, when an intruder is detected within the protected space. To defeat such surveillance systems, intruders may try to tamper with or sabotage the system so that it will not generate an alarm signal when the intruder enters the protected space.
Intrusion detection system typically employ a number of different individual motion detectors that are mounted on a building structure such as a wall of the building. When an intruder seeks to tamper with such a detector, they may remove the cover or the entire unit from the wall. Although various methods of detecting such tampering with individual detectors have been developed, an improved, reliable and cost effective method of detecting such tampering is desirable.